1. Field of the Invention
The present invention relates to lamp holders, and, more particularly, to fluorescent lamp holders.
2. Description of the Related Art
Fluorescent lamps, as known, include a glass tube coated on the inside with phosphor powders which fluoresce when exited by ultraviolet light. The glass tube is filled with rare gases (such as argon, neon, and krypton) and a small amount of mercury, and operates at a relatively low pressure. Electrodes are mounted within the glass tube and emit electrons during operation. The electrons are accelerated by the voltage across the tube until they collide with mercury atoms, causing the mercury atoms to be ionized and excited. When the mercury atoms return to their normal state, photons corresponding to mercury spectral lines in both the visible and ultraviolet region are generated, thereby exciting the phosphor coating on the inside of the tube to luminance.
To start a fluorescent lamp, electron emission from the electrodes may be induced in one of two ways. First, a filament electrode may be heated by passing current therethrough. Secondly, a high voltage which is sufficient to start an electric discharge in the lamp may be applied across the lamp without preheating the electrodes. Instant start circuits which are commonly used today typically employ the latter method of inducing electron emission from the electrodes. Instant start circuits use a ballast which applies a high voltage (e.g., up to 848 VAC) at a high frequency. Such instant start ballasts are much more energy efficient than older style ballasts which heat the electrodes. The ballasts are wired from their mounting location to a fluorescent lamp assembly.
Such fluorescent tubes come in a variety of styles and thus are used in a variety of applications. One such application is in commercial refrigeration illumination. Generally, a fluorescent lamp holder or assembly for such applications includes a fluorescent lamp surrounded by a protective plastic tube that are both retained on each end by a cap structure. One cap structure covers terminals on one end of the fluorescent lamp and the connection wires. The other cap structure couples the terminals of the other end of the fluorescent lamp to electrical power, generally by a power cord. Wires run the length of the protective plastic tube for appropriate connection to the terminals on the other end of the fluorescent lamp. Each cap structure is retained to the protective plastic tube by metal clips. The lamp assembly is generally retained within the refrigerator or freezer by clips. The power cord from the lamp assembly is wired into the power of the refrigerator. The above fluorescent lamp holder is, by its nature, disposable and not waterproof. Replacement of the fluorescent tube in the prior art holders is usually not recommended. Further, when the fluorescent lamp goes out, the entire holder must be unwired, with a new holder to be rewired. Additionally, because the lamp assemblies are typically disposed in a cold environment, start-up of the fluorescent lamp may be difficult.
What is needed in the art is a fluorescent lamp holder which prevents electrical arcing between a conductor of the lamp holder and the contact pins of a fluorescent lamp.
What is also need in the art is a fluorescent lamp holder that is waterproof for use in a moisture-laden environment.
Further needed in the art is a fluorescent lamp holder that allows replacement of the fluorescent lamp.
Still further needed in the art is a fluorescent lamp assembly that provides thermal insulation for the fluorescent lamp relative to the ambient environment.
Still even further needed in the art is a fluorescent lamp assembly that functions better in cold environments.